Subgrid Models for Two-Dimensional Turbulence based on Lagrangian Spectral Theory
An LES subgrid model in the enstrophy cascading range of two-dimensional turbulence is proposed. The effects of the subgrid scales are modeled by a Langevin-type equation containing an eddy damping factor and a random force. The eddy damping and forcing are expressed as functionals of the energy spectrum using the Marko-vianized Lagrangian renormalized approximation (MLRA), a Lagrangian spectral the-ory without ad hoc parameters. It is found that the enstrophy spectrum predicted by MLRA-LES (N = 1282) agrees well with the DNS data (N = 10242) for forced turbulence. The growth of the error spectrum predicted by the MLRA-LES is also found to be very similar to that of the DNS. Some simplifications of the eddy damping factor are proposed for application to global-scale flow prediction. One model is found to give predictions of the enstrophy spectrum and error growth which are comparable to the MLRA-LES results.
KeywordsLarge Eddy Simulation Random Force Error Growth Subgrid Scale Vorticity Contour
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